title: An induced blood pressure rise does not alter upper airway resistance in sleeping humans.
abstract: Sleep apnea is associated with episodic increases in systemic blood pressure. We investigated whether transient increases in arterial pressure altered upper airway resistance and/or breathing pattern in nine sleeping humans (snorers and nonsnorers). A pressure-tipped catheter was placed below the base of the tongue, and flow was measured from a nose or face mask. During non-rapid-eye-movement sleep, we injected 40- to 200-microgram i.v. boluses of phenylephrine. Parasympathetic blockade was used if bradycardia was excessive. Mean arterial pressure (MAP) rose by 20 +/- 5 (mean +/- SD) mmHg (range 12-37 mmHg) within 12 s and remained elevated for 105 s. There were no significant changes in inspiratory or expiratory pharyngeal resistance (measured at peak flow, peak pressure, 0.2 l/s or by evaluating the dynamic pressure-flow relationship). At peak MAP, end-tidal CO2 pressure fell by 1.5 Torr and remained low for 20-25 s. At 26 s after peak MAP, tidal volume fell by 19%, consistent with hypocapnic ventilatory inhibition. We conclude that transient increases in MAP of a magnitude commonly observed during non-rapid-eye-movement sleep-disordered breathing do not increase upper airway resistance and, therefore, will not perpetuate subsequent obstructive events.
authors.affiliation: Department of Preventive Medicine, University of Wisconsin-Madison 53705, USA. crwilson@lynx.neu.edu
authors.forename: C R
authors.initials: CR
authors.lastname: Wilson
authors.forename: S
authors.initials: S
authors.lastname: Manchanda
authors.forename: D
authors.initials: D
authors.lastname: Crabtree
authors.forename: J B
authors.initials: JB
authors.lastname: Skatrud
authors.forename: J A
authors.initials: JA
authors.lastname: Dempsey
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000328:Adult; D000403:Airway Resistance / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D017286:Polysomnography; D015656:Respiratory Mechanics / Q000187:drug effects / Q000502:physiology; D012890:Sleep / Q000502:physiology*; D012913:Snoring / Q000503:physiopathology
chemical_list: D000316:Adrenergic alpha-Agonists; D002245:Carbon Dioxide; D010656:Phenylephrine